During the last three years there has been exponential growth in the availability of information from and use of data communications networks. Users of the Internet, intranets, enterprise networks and other data communications networks are able to make travel reservations, query bank accounts, access corporate databases, obtain stock quotes, send and receive e-mail, purchase wine, etc., from almost anywhere in the world, as long as they have the ability to connect to these networks from a local access point.
Much of the referenced growth can be attributed to the development of World Wide Web (WWW) browsers such as NCSA's Mosaic and Netscape's Navigator, which have given a graphical user interface to the formerly text-based networks, and on the widespread acceptance of the TCP/IP protocols that these Web Browsers utilize. By 1998, it is estimated that as many as 70% of all computers worldwide will use the TCP/IP protocols as a standard for data communications.
As the number of users who access data communication networks has increased, so has the volume of information transferred increased. In addition, as modem speeds have increased, the demand for more "content" has increased. There is a general trend that with information delivery, "more is better." As a result of these trends, the average user is now able to send and receive audio, video and voice across the typical data communications network.
As users and technology push the boundaries of the networks, limitations and limiting factors evolve or play a greater role in application development. One limitation of any data communication network is the size of its "pipe". That is, how much data can be transmitted across a network at any given time. The concept of a "pipe" can be compared to amperage flowing through an electric circuit or water flowing through a garden hose.
All data pipes, no matter how large, have limitations related to throughput. This concept can be thought of as bandwidth-constrained. Historically, the capacities of available data pipes have not been an issue in the use of the networks. However, as the number of users has increased and the amount of data those users are transmitting has increased, the capacities of the pipes has become a topic of discussion. Most of the discussions have centered on wireline or wired data communications networks. Some portions of those pipes are becoming bandwidth-constrained, and future uses of new technology may pose additional limitations. An example of a type of bandwidth-constrained or R.sub.-- Link wired network is the uplink side of some cable networks.
During the same period of time that the explosion in users occurred on wireline networks, the development of wireless networks was accelerating in pace. The ability to deliver lower cost "anytime, anywhere" access to wireless data communications users became a reality on the drawing board and as a result, service providers who could deliver this type of access began or increased deployments. Generally, due to speed and throughput, wireless networks are thought of as bandwidth-constrained. Examples of bandwidth-constrained or R.sub.-- Link wireless networks include circuit-switched cellular, CDPD, SMR, ESMR, packet radio,satellite, etc.
Other important factors in the deployment of wireless data access is the development of handheld, mobile and portable devices such as laptop computers, PDAs, two-way pagers, small form-factor wireless data modems and data-ready cellular phones. It is clear the future of data communications includes access from anywhere using wireless data networks. More so with wireless networks than wireline networks, capacities and throughputs pose serious limitations on the applications and users of these networks.
Although the applications and wired/wireless devices that exist today can be used together to access the data networks described earlier, they can be both prohibitively costly and unacceptably slow. Most existing applications and protocols have been designed for use over high-speed, high-bandwidth networks and as a result are not bandwidth-efficient when operated over lower-speed, lower-bandwidth wide area data networks (wireless or not). The applications and their native protocols (e.g. a Web browser using HTTP) have inherent limitations due to access speed, bandwidth, number of users, the protocol itself, etc. However, their widespread use makes it unlikely that a change in the design of the application to use a more efficient protocol, will take place anytime soon.
What is needed is a methodology that effectively unites these two worlds. Previous inventions provided basic links between wireless users and fixed wired networks, and some addressed differences in protocols between the two. But, none allowed the use of existing applications and their protocols that are efficient in high-speed, high-bandwidth portions of a data communications network (hereafter referred to as "NR.sub.-- Link"), in R.sub.-- Link portions where native functionality is maintained and efficiency and throughput are improved.
C. Perkins, Network Address Management for a Wired Network Supporting Wireless Communication to a Plurality of Mobile Users; for Transmitting Information, U.S. Pat. No. 5,159,592 (Oct. 27, 1992) discloses a local gateway coupled between a wireless LAN and the wired network for communication with a mobile communication unit.
C. Perkins and J. Rekter, Shortcut Network Layer Routing for Mobile Hosts, U.S. Pat. No. 5,442,633 (Aug. 15, 1995) disclose the routing of packets between mobile and fixed hosts which are coupled to a network. The disclosed method includes the transmission of packets "from the mobile host to a second, destination host on the network through a wireless link that is established between the mobile host and a base access station that serves a current physical location of the mobile host." Packets originating from the mobile host arrive at the fixed host with an "Internet Protocol Loose Source Routing" option that includes a network address of the base access station. While this methodology makes a network connection between the mobile host and fixed host, it fails to minimize the amount and size of packets sent and received by the mobile host over the wireless link.
J. Hart, System for Expanding Network Resources to Remote Networks, U.S. Pat. No. 5,423,002 (Jun. 6, 1995) discloses a system for interconnecting networks, wherein "a routing adapter extends a remote routing interface of the boundary router transparently across the communication link" to a second network.
R. Bird, K. Britton, T. Chung, A. Edwards, J. Mathew, D. Posefsky, S. Sarkar, R. Turner, W. Chung, Y. Yeung, J. Gray, H. Dykeman, W. Doeringer, J. Auerbach, and J. Wilson, Compensation for Mismatched Transport Protocols in a Data Communications Network, U.S. Pat. No. 5,224,098 (Jun. 29, 1993) disclose a transport layer protocol boundary architecture, in which transport functions are compared and compensated for between a first application program and a second remote application. If compensations are necessary, de-compensation operations can be performed before the data is delivered to the remote application program.
The prior art thus provides basic connections between wireless devices and fixed networks and hosts, and addresses protocol differences, but does not provide a methodology for reducing or minimizing data transmission over the bandwidth-constrained portions of a data communications network (R.sub.-- Link). The development of a cost-effective and efficient data communications system and methodology between wireless devices and network-based information and services would constitute a major technological advance.